Note: Descriptions are shown in the official language in which they were submitted.
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DENTAL IRRIGATOR
Field of the Invention
The present invention relates to the field of dental irrigation devices. In
particular, the present invention relates to an irrigation device which
receives irrigant solution at relatively low pressure, and delivers it at
relatively high pressure through the hollow interior of an endodontic file.
Background of the Invention
During a root canal procedure, the dentist (or, endodontist) typically uses an
endodontic file to remove tissue remnants to clean and shape the canal.
While working the canal becomes clogged with dentin mud and debris,
which interferes with the procedure. Since prior art root canal procedures
are almost exclusively carried out using solid drills, the drill must be
periodically withdrawn from the canal in order to introduce an antiseptic
irrigant solution to flush out unwanted debris. The irrigant solution must to
be supplied at relatively high pressure in order to effectively wash the
debris out of the canal. Additionally, since the reason for performing a root
canal procedure is frequently an infection of the pulp in the root canal and
also because of the presence of large numbers of pathogens in the mouth, it
is also necessary to thoroughly disinfect the canal, especially before
obturation of the canal space and preferably during the course of the entire
procedure.
US 4,608,017 discloses a conventional endodontic irrigating instrument for
irrigating the root canal of a tooth with an irrigating liquid. The instrument
is a hand-piece similar to conventional dental hand-pieces. There is an
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aspiration needle at the distal end that is designed to insert into a clean or
partially cleaned root canal. The instrument is connected directly to the
office water and compressed air supplies. Water under pressure can flow
through the instrument and out at the distal end in the form of an annular
water jet surrounding the aspiration needle. The compressed air flows
through a Venturi tube inside the instrument to create a partial vacuum
that is used to draw the water and debris out of the canal through the
aspiration needle. The flow rate and the pressure of the water and air are
controlled manually by regulating valves. When it is desirable to perform
irrigation with irrigating solutions such as peroxide solution instead of
rinsing water, a container containing such solution may be provided and
pressurized by introducing compressed air from a dental unit. The
pressurized irrigating solution is then fed by a supply conduit to the head of
the instrument.
The endodontic irrigating instrument disclosed in US 4,608,017 is a
dedicated device that is separate from the hand-piece used to shape and
clean the canal with the endodontic file. In use the dentist must interrupt
his work with the file, put it aside, pick up the irrigating instrument,
operate it for a period of time, and then put it aside before continuing to
work with the file.
US 4,973,247 discloses a typical gas driven dental handpiece assembly. The
assembly comprises a supply of compressed gas which operates a turbine for
driving a high speed dental cutting or drilling tool. When working with a
dental tool of this type a coolant and/or irrigant solution must be provided
because of the frictional heat generated and to rinse away debris. The
invention described in this patent is an addition to the hand-piece that
provides an alternative to using the community water supply as a coolant or
propellant fluid in order to provide a sterile working environment. The
addition is a cartridge divided by a diaphragm containing coolant liquid on
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one side of the diaphragm. A mechanism is provided to allow the operator of
the hand-piece to controllably divert the turbine drive gas to the empty part
of the cartridge. The gas introduced into the cartridge exerts pressure on the
diaphragm causing the coolant liquid to move under pressure out of the
cartridge and toward the head of the dental tool where it is sprayed onto the
work area from an opening located near the connection of the tool to the
hand-piece. The sterility concerns are addressed by supplying a new
cartridge for each patient.
US 6,527,551 discloses a dental irrigation device aimed at overcoming the
drawbacks of prior art systems that are cumbersome, complex and require
permanent installations. The invention comprises an irrigant reservoir
containing irrigant such as isotonic saline, water or medicaments,
mountable on a dental delivery system. Pressurization means such as a
standard source of air pressure for pressurizing irrigant is connectable to
the reservoir. A handpiece is joined to the reservoir via a supply channel
and comprises a standard dental handpiece interface for adapting with
dental tools for dispensing irrigant, such as syringe irrigation tips.
The patents described above are typical of the approaches made in the prior
art to providing irrigant solution to the site of the dental procedure. None
of
the prior art irrigant delivery systems of the prior art solve the basic
problem of continuously supplying irrigant to the interior of a root canal
during the cleaning and shaping phases of a root canal procedure. The
problem is not limited to merely supplying the solution but also to supplying
it at sufficient pressure to drive out the debris, to maintain the sterility
of
the surgical environment, and to supply it using a system that is convenient
for the operator and as comfortable as possible for the patient.
It is an object of the present invention to provide a dental irrigation device
that can be used with a suitable endodontic file to allow continuous flushing
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of the root canal while the fi.l.e is inserted into the canal and engaged in
cleaning and shaping it.
It is another object of the present invention to provide a dental irrigation
device which receives fluid at relatively low pressure and delivers the fluid
to the at relatively high pressure to the interior of the canal..
It is an additional object of the present invention to provide an irrigation
device that can be retrofitted to existing dental hand pieces.
Additional objects and advantages of the present invention shall become
apparent as the description proceeds.
Summary of the Invention
The invention is a dental irrigator for delivering irrigant solution from an
irrigation solution reservoir to the site of a dental procedure. The irrigator
comprising:
a) a hollow dental tool modified by the addition of one or more curved
blades either formed directly on the neck of the tool or on a sleeve
attached coaxially to the neck;
b) one or more inlets associated with each of the curved blades;
c) a housing that provides a watertight volume surrounding the
inlets while allowing the tool to be freely moved with respect to
the housing; and
d) a supply hose, which conducts the irrigant solution at relatively
low pressure from the reservoir to the housing.
When the dental tool is attached to the distal end of a dental hand-piece and
the hand-piece is activated causing the tool to move, irrigation solution
enters the hollow interior of the neck of the tool and, as a result of the
forces
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created by the motion of the curved blades, is delivered at relatively high
pressure to the site.
When activated the hand-piece may impart a rotational, a reciprocating
linear, or a vibrational motion to the hollow dental tool.
When the hand-piece imparts a rotational motion to the hollow dental tool,
the curved blades are preferably curved impeller blades. The curved
impeller blades may extend either outwardly from the outer surface or
inwardly into the interior of the neck or sleeve. In preferred embodiments
the curvature of the curved impeller blades matches the shape of a cardioid
curve.
In an embodiment wherein the hand-piece imparts a reciprocating linear
motion to the hollow dental tool, the curved blade is located in the hollow
interior of the neck or the sleeve.
In a preferred embodiment, the hollow dental tool of the dental irrigator of
the invention is an endodontic file for use in a root canal procedure.
Brief Description of the Drawings
- Fig. 1 shows an overall view of the invention;
- Figs. 2a and 2b illustrate an endodontic file having an open lattice-
like structure;
- Fig. 3 illustrates an enlarged view of a portion of the irrigation device
of the present invention.
- Fig. 4 shows an enlarged view of the neck of the file;
- Fig. 5 shows a cross-sectional view taken in pane A-A of Fig. 4;
- Fig. 6 shows the cardioid shape of the impeller blade;
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- Fig. 7 an embodiment of the present invention in which the impeller
blades are located on a sleeve attached to the neck of the file;
- Fig. 8 shows another design of the impeller blades;
- Fig. 9a schematically shows a blade for an irrigator designed to be
used with dental hand-piece that imparts a reciprocating linear
motion to the hollow dental tool; and
- Fig. 9b and 9c symbolically show respectively the movement
resistance vector during the upstroke and downstroke of the blade of
Fig. 9a through a solution.
Detailed Description of the Preferred Embodiments
The invention is a dental irrigator, i.e. a delivery system that delivers
irrigant solution at a relatively high pressure to the site of a dental
procedure through the interior of a rotatable, hollow dental tool that is
attached to the distal end of a dental hand-piece. The dental tool is modified
by the addition of one or more curved blades and at least one inlet
associated with each of the curved blades. The blades and inlets are either
formed directly on the neck of the tool or on a sleeve that can be slid over
or
into the neck and attached to the neck or can serve as a collar to connect the
neck of the tool to the dental hand-piece. The irrigant is delivered at low
pressure, typically at or slightly over zero atmosphere gauge pressure to a
housing that provides a watertight volume surrounding the inlets. The tool
is attached to the distal end of a dental hand-piece. When the hand-piece is
activated causing the tool to rotate, move reciprocally in a longitudinal
direction or vibrate the irrigant is drawn into the hollow interior of the
tool
by means of the forces created by the motion of the blades.
The term, "irrigant solution" as used herein refers to any fluid solution for
washing debris from a root canal, and/or for cooling a tooth and/or dental
tool, and/or for disinfection of the canal.
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The invention was developed to be used for root canal treatment in
conjunction with a new type of endodontic file invented by the inventor of
the present invention. The endodontic file was described previously in
published international patent application W02005/070320, by the same
applicant, the description of which, including publications referenced
therein, is incorporated herein by reference. The use of this drill to perform
root canal procedures has been chosen in order to illustrate the principles of
the invention; however, as the description herein develops it will become
apparent to skilled persons that the present invention can be adapted to be
used for many other applications and with many different types of hollow
tools.
Fig. 1 shows an overall view of the invention. In Fig. 1 can be seen rotatable
endodontic file (10) joined at the proximal end of its neck (120) to a
conventional dental hand piece (12). File (10), shown in Fig. 1 and in an
enlarged view in Figs. 2a and 2b in perspective and side views respectively.
Dental file (10) is made of a shaped memory material, preferably nickel
titanium alloy (Nitinol). In the figures is shown an embodiment of the tool in
its expanded configuration, which has the cylindrical shape that was
imposed upon it during manufacture. The walls of the neck (120) are solid
and are gripped by either the dental hand piece (12) or can be attached to a
handle for manual use. The main part of the body of dental file (10) is an
open, lattice-like structure made up of longitudinal elements (6) that run
the length of the instrument from neck (120) to tip (4) and short
circumferential elements (2) that connect adjacent longitudinal elements (6).
The structure of the file allows it to be compressed reducing its diameter as
it is inserted into a root canal. As the file (10) rotates, material is
scraped
from the wall of the root canal and passes through the openings in the
lattice structure of the body of dental file (10) into the hollow interior
from
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which it can easily be removed without stopping rotation of the instrument
or withdrawing it from the root canal by use of suction or by causing a
stream of clean irrigant solution to flow into the file. The shaped memory
property causes the f.le to continuously try to expand from its compressed to
its expanded configuration. Therefore, as material is scraped from the wall,
the file expands keeping constantly in contact with the canal wall and
allowing removal of material from the wall without changing the inherent
shape of the canal.
The novel design of the drill shown in Figs. 2a and 2b provides the
possibility for fluids, such as antiseptic or saline solution, to continuously
flow into and out of the root canal, either through the center of the
instrument or between the outer surface of the instrument and the canal
wall, while the instrument is working, thus saving valuable time and
improving the debridement and disinfection procedures. The constant flow
increases the efficiency of filing and prevents clogging of the canal with
dentin-mud and debris.
A preferred embodiment of the irrigation system of the present invention
will now be described with reference to Fig. 1 and Fig. 3, which is an
enlarged bottom perspective view of area "A" in Fig. 1. The system of the
invention is generally described by the numeral (100). The main feature of
irrigation system 100 is the three curved impeller blades (122) that have
been created on the neck (120) of the drill (10). The blades (122) are spaced
equidistantly along the circumference of neck (120) and extend curvedly
outward from neck (120) in the direction of rotation of dental file (10),
which
is indicated by arrow (14) (see Fig. 3). Irrigation device (100) further
comprises a housing (112) surrounding impeller blades (122), as described
herein below.
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Although three blades (122) are shown in the figures, it is understood that
fewer or more than three blades (122) may be provided, depending on the
diameter of neck (120), among other parameters.
Fig. 4 shows an enlarged view of the neck (120) of the file. Fig. 5 shows a
cross-sectional view taken in plane A-A of Fig. 4. An inlet (124) is created
through the wall of the neck (120) at the inside of the curvature opposite
each impeller blade (122). If the area of neck (120) containing the impeller
blades (122) and associated inlets (124) is surrounded by a liquid, then when
the file is rotated rapidly by the hand-piece, a low pressure area will be
created on the inner side of the curved impeller blades, causing the liquid to
enter the interior of the drill through inlets (122). The liquid that enters
through inlets (122) will be directed towards the bottom of the file, i.e.
into
the root canal, at a high velocity and much higher pressure relative to the
pressure of the liquid that is supplied at the outside of the neck (120).
The design of the impeller blades is not a part of the present invention.
Skilled persons will be able to use well known methods of fluid flow to arrive
at the optimal design while taking into account such factors as the inner
and outer diameters of the neck (120), flow rate, supply pressure, desired
delivery pressure, viscosity of the liquid, etc. The inventor has determined
that excellent results can be obtained by making the curvature of the
impeller blade (122) match the shape of a cardioid curve (126) as shown in
Fig. 6.
In the embodiment of the invention shown in Figs. 3 to Fig. 6, impeller
blades (122) are integrally formed out of neck (120), i.e. blades (122) and
neck (120) are manufactured as a single piece. In an alternative
embodiment, as shown in Fig. 7, the impeller blades (122) are formed on a
separate sleeve (121). Sleeve (121) is positioned around neck (120) such that
inlets (124a) are aligned with holes (124b) in neck (120). Sleeve (121) is
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fixed in place by conventional means such as a set screw, or alternatively,
sleeve (121) may be threadingly engaged with neck (120). In Fig.7, sleeve
(121) is shown shortened in order to show its orientation with respect to
neck (120), but in reality, either the sleeve or neck must extend
longitudinally enough to allow it to be attached to the hand-piece.
In yet another embodiment of the invention shown in Fig. 8, the impeller
blades (132) extend curvedly inwards into the hollow internal space of neck
(110). In this embodiment the impeller blades can be formed on a bushing
that is inserted into the hollow neck (120).
In order to supply the irrigant to the impellers, a watertight housing (112)
is
provided as part of the irrigator. Many different possible embodiments of
housing (112) are possible. In all cases, the dental file (10) must be allowed
to freely rotate while the housing (112) itself is constrained in some manner
from rotating relative to the hand-piece. To allow rotation of file (10) while
preventing irrigant solution from leaking out of housing (112), a seal such as
an o-ring is situated at the upper and lower ends of housing (112) and a
suitable lubricant, e.g. silicon grease, is applied to the o-ring to reduce
friction as the tool rotates. The housing can be permanently attached to the
distal end of the hand-piece (12), it can be attachable to and detachable from
the distal tip of the hand piece (12), or it can take the form of a capsule
that
is either permanently attached to or slid onto the file. In the latter case an
arrangement is provided to prevent rotation of the capsule relative to the
hand-piece.
A connector is provided on housing (112) in order to connect a supply hose
(110), which is provided to conduct the irrigant from the reservoir (not
shown in any of the figures) to the interior of the housing. A section of
supply hose (112) may pass through the hand-piece (12) as shown in Fig. 1
or supply hose (110) may directly join the reservoir to housing (112). In
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preferred embodiments a valve of some sort is provided to allow the flow of
irrigant to the housing, i. e. into the root canal, to be controlled by the
dentist. As is customary, the valve is conveniently activated by means of a
foot pedal.
In the embodiment described herein above, the dental tool is attached to a
hand-piece that imparts rotary motion to the tool. The invention can also be
used with hand-pieces that impart reciprocating linear motion: to the tool,
normally in the direction of the longitudinal axis of the tool, or vibrational
motion in any direction.
In Fig. 9a is schematically shown a blade 200 inserted into the neck 120 of a
hollow dental tool, for example the endodontic file described herein above.
Not shown in Fig. 9a is the inlet into the interior of the neck and the
housing that surrounds it. The tool is connected to a dental hand-piece that
imparts a reciprocating linear motion to the tool, moving the tool and
attached blade up and down relative to the housing. The blade is designed
so that on the down stroke most of the liquid that is inside the "cup" of the
blade is swept downward, as shown in Fig. 9c. On the upstroke the blade
cuts upward through the liquid, pushing it against the walls of the housing
and forcing it downward into the neck around the sides of the blade. The
arrows that are shown in Figs. 9b and 9c symbolically represent the
movement resistance vector as the blade moves up and down through the
solution inside the neck of the dental tool.
In the preferred embodiment, the irrigant solution reservoir is a plastic bag
similar to an infusion bag. The reservoir can be laid on the table that is
attached to the dentists chair and used to lay out the instruments used
during the procedure. As long as the table is essentially at least on the same
level as the housing (112) the action of the impellers will be sufficient to
draw irrigant from the bag at a rate sufficient to remove the debris from the
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root canal. The irrigator (100) of the invention therefore avoids the problem
of gravity fed irrigators of having to hang the supply container high above
the patient in order to provide enough elevation to allow irrigant solution to
flow to the treatment area under the influence of gravity and to arrive at a
high enough pressure to be effective.
Any other type of reservoir known in the art or devised by skilled persons
that can deliver the irrigant to the housing (112) at a gauge pressure of
essentially zero may be used with the irrigation device of the invention. For
example, the irrigant may be supplied in a plastic bag, which is placed in a
container comprising a moveable surface that, with the aid of springs
presses against the bag forcing the liquid inside into the supply hose (110).
Another more expensive alternative is for the reservoir to be a syringe and a
syringe pump is used to force irrigant solution out of the syringe. The pump
may be arranged to push a small amount of irrigant solution out of the
syringe at a constant rate, or at preset time intervals, or the pump may be
manually actuated.
Typically the endodontic file (10) is discarded after each procedure and
similarly it is preferred that all of the components of the irrigation system
of
the invention are disposable also although it is also possible to manufacture
all or part of the system from sterilizible materials allowing them to be
reused.
While some embodiments of the invention have been described by way of
illustration, it will be apparent that the invention can be carried into
practice with many modifications, variations and adaptations, and with the
use of numerous equivalents or alternative solutions that are within the
scope of persons skiIled in the art, without departing from the spirit of the
invention or exceeding the scope of the claims.
